Personal thermal device



Oct. 12, 1965 R E. COLEMAN, JR., ETAL 3,211,216

PERSONAL THERMAL DEVICE Original Filed Sept. 13. 1952 5 Sheets-Sheet 1INVENTOR.

c (.KACKEN norm Rosem E. COLEMAN JR. BY CALVIN D. MA

@N 0N v lx u a @m vN Oct 1965 R. E. COLEMAN, JR., ETAL 3,

PERSONAL THERMAL DEVICE 5 Sheets-Sheet 2 Original Filed Sept. 13, 1952INVENTOR. Rosuu E. COLEMAN JR. (.ALVtN D. MMCKMKEM Oct. 12, 1965 R. E.COLEMAN, JR., ETAL 3,211,216

PERSONAL THERMAL DEVICE Original Filed Sept. 13, 1952 5 Sheets-Sheet 3 FR0 M m. ma nu TO PUMP FROM BLANKET INVENTOR.

ROBERT E. COLEMAN n.

, CALVIN D. MACCRACKEN A'n'onuev Oct. 12, 1965 R. E. COLEMAN, JR., ETAL3,211,216

PERSONAL THERMAL DEVICE Original Filed Sept. 13. 1952 5 Sheets-Sheet 5THERMOPUMP T THERMOPUMP JNVENTOR. Rosem E. COLEMAN JR, (ALVIN D.MACCRACKEN ATTORNEY Unitd States Patent 3,211,216 PERSONAL THERMALDEVICE Robert E. Coleman, in, Packanack Lake, and Qalvin D.

MacCracken, 'Ienatly, Ni, assignors, by mesne assignments, to CalrnacCorporation, Boston, Mass, a corporation of Massachusetts Originalapplication Sept. 13, 1952, Ser. No. 309,416, now Patent No. 3,112,792,dated Dec. 3, 1963. Divided and this application Nov. 24, 1961, Ser. No.160,387

2 Claims. (Cl. 165-46) This is a division of application Serial No.309,416, filed September 13, 1952, now patent No. 3,112,792.

This invention relates to improvements in Personal Thermal Devices, andparticularly to improved personal heating and cooling apparatus of thetype wherein a temperature controlling fluid is circulated through athin, flexible heat exchange structure such as a blanket, a garment orthe like.

It is among the objects of the present invention to provide an improvedpersonal thermal device of the foregoing type that is small and light inweight, that can be made as an entirely self-contained, readily portableunit, that is inexpensive to manufacture, that involves practically nomoving parts, that will operate under a wide variety of ambienttemperature conditions, and that is suitable both for heating and forcooling.

In accordance with preferred embodiments of the invention, the foregoingand other related objects and ad vantages are attained in apparatuswherein a thin, flexible heat exchange structure, such as a garment, ablanket or a illowcase insert, is provided with liquid conductingpassages through which liquid is circulated by means of a head operatedpump (referred to herein as a thermopump). As will be brought out morefully hereinafter, such an arrangement can be embodied in a very smallapparatus package. Depending on the specific use for which the apparatusis designed, the primary heat source for the thermopump may comprise anelectrical heater, a small flame supported by a combustible fluid, or avariety of other similar heat sources.

Because of the simplicity and compact and c0nfigura tion of thethermopump, the apparatus has unusual versatility, and finds applicationin a variety of uses for which comparable prior art devices are oflimited or no utility. Moreover, where heating is required, the heatenergy is used in a dual capacity as a source of motive power and forheating the circulated fluid.

A more complete understanding of the invention can be had by referenceto the following description of illustractive embodiments thereof, whenconsidered in connection with the accompanying drawing wherein FIG. 1illustrates a heated blanket arranged in accordance with the invention,with a portion of the blanket surface broken away to show the interiorconstruction,

FIG. 2 is a cross-sectional view of the blanket of FIG. 1, taken on theline 22 of FIG. 1,

FIG. 3 is a perspective View of a header unit used in the blanket ofFIG. 1,

FIG. 4 is a fragmentary View of a thermopump, showing electrical heatingof the pump generator,

FIG. 5 illustrates a heated suit arranged in accordance with theinvention.

FIG. 6 illustrates a thermopump and fuel container assembly suitable foruse in the system of the present invention,

FIGS. 7-9 illustrate modified forms of fluid heating circuits embodyingthe invention,

FIG. 10 illustrates a cooling and heating system embodying theinvention,

FIG. 11 is a cross-sectional view of the heat exchange structure of FIG.10, taken on the line 11-11 of FIG. 10, and

FIGS. 12-14 illustrate modified forms of fluid cooling and heatingcircuits embodying the invention.

Already indicated, the particular heat exchange structure through whichthe temperature controlling fluid is circulated in accordance with thepresent invention may take any one of a variety of different forms. Ingeneral, what is contemplated is a flexible structure or web of materialcapable of conforming to or serving as a covering for part or all of thehuman body, and may comprise a garment, such as a jacket, coveralls orthe like, bedclothing, such as a sheet, a blanket, a sleeping bag apillow insert or a mattress cover, or similar items of personal use.

By way of introduction, the invention will first be described asembodied in a heated blanket.

Referring to FIGS. 1 and 2 of the drawing, a heated blanket 8 arrangedin accordance with the invention cornprises a thin, flexible two-layerheat exchange structure It), 11, provided between the fabric layers 10,11 with liquid conducting passages 12 extending throughout the blanketand through which heated liquid is circulated by a thermopump 14.

The superposed fabric layers 10, 11 are sewn together along the outsideedges and along spaced line 13 to provide channels for holding flexibletubing, such as rubber or plastic tubes, forming the liquid conductingpassages 12 For clarity, only a small number of relatively largecross-section tubes 12 are shown in FIGS. 1 and 2. In actual practice,tubing of capillary dimensions is preferably used, not only to decreasethe quantity of circulating liquid in the blanket structure and to makethe surface irregularities due to the tubing less noticeable, but alsoto avoid stoppages due to kinking of the tubing 12. For example, tubingwith an inside diameter and a wall thickness of, say 40 mils, is foundto be appropriate. A suitable material for the tubing in a plasticmaterial, such as one of the so-called vinyl resins, polyethylene, orthe like. Furthermore, instead of a six tubing circuits shown in thedrawing, twenty or more such circuits may be used to distribute the heatmore uniformly.

The loops of tubing 12 are connected between a pair of header units 16,18, one of which (16) constitutes an input header and the other of which(18) constitutes a return header. The arrangement is such that heatedliquid will enter the blanket through the input header 16, flow throughthe various loops of tubing 12, in parallel and flow out through theheader 18. This parallel flow arrangement has the advantage that itequalizes the heating effect across the blanket, and also reduces thepressure drop or resistance to liquid flow in the tubing 12, as comparedwith a series path through a single tube looped back and forth acrossthe entire blanket.

It has been found preferable to use small diameter tubing throughout theentire blanket and to connect this tubing to small compact headers orjunction units 16, 18 rather than having large diameter header tubesextend along the edge of the blanket. The reason for this is that iflong header tubes are used, they must be large enough in diameter tocarry the liquid for substantially all of the circuits 12 withoutappreciable pressure drop. On the other hand, tubing of the requireddiameter is very likely to kink and materially reduce or even completelycut off the flow of liquid if made flexible enough to conform to foldsand the like in the blanket. The header units 16, 18 can be very compactassemblies, fully rigid to obviate kinking and yet extending over nomore than one or two square inches of blanket surface area.

As shown in detail in FIG. 3, for example, each header 3. unit maycomprise a shortlength of metal tubing 20, partially flattened to anoval shape throughout a portion of its length, and having the ovalshaped end 20a sealed off. In the oval shaped portion of the tube 20,short stubs 24 of very small diameter tubing are soldered into the tube20 in the general plane of the major axis of the oval to connect to theblanket circuit tubes 12. The round end 20b of the header tube 20 isadapted to be inserted in the end of a flexible tube (26 or 28 in FIG.1), leading to or from the blanket 8 and the thermopump 14.

The thermopump 14 of FIG. 1 corresponds generally to the pump describedin US. Patent 2,553,817-Kleen. Briefly, such a pump comprises a vaporgenerator chamber in the form of a tube 29, of inverted U-shape, withinwhich to form vapor when heat is applied to the tube 29 from some sourcesuch as an open flame 30. The end of one leg of the U-tube 29 isconnected through a smaller diameter U-shaped vapor transfer tube 32 toa vertical tube 34 which constitutes a vapor condenser chamber. Thelower end of the condenser tube 34 and the other leg of the generator 29are connected through a reservoir 36. The generator 29, the vapor tube32, the condenser .34 and the reservoir 36 constitute a closed loopwhich is coupled to the blanket passages 12 through a pair of checkvalves 37, 39, the flexible tubing 26, 28, and the headers 16, 18.

The operation of the thermopump 14 is as follows:

When the heat of the flame 30 acts on the generator tube 29 to vaporizethe liquid therein, vapor will collect in the upper portion of the U,raising the pressure in the pump and forcing liquid to flow downwardlythrough the leg of the generator tube and upwardly through the vaportube 32 and the condenser 34. This, of course, will force liquid to flowout through the check valve 39 and into the blanket circuits 12 throughthe header 16 as the blanket circuits expand slightly to accept theliquid forced into them. When the liquid level in the pump has beenforced down by the vapor to the lowermost point in the vapor tube32,,vapor will being travelling up through the vapor tube 32. This willcreate a hydrostatic unbalance between the liquid in the generator andcondenser columns, tending to cause liquid to flow downwardly throughthe condenser tube 34 and upwardly intothe generator 29. Thiscounter-clockwise flow of liquid in the pump will force all the vaporout of the generator chamber and into the condenser chamber wherein thevapor will condense, thereby decreasing the pressure in the pump andcausing liquid to be suctioned into the pump through the check valve 37from the return header 18 and the return tube 28. Thereupon, the systemwill temporarily come to rest until a new volume of vapor begins tocollect in the generator tube, whereupon the entire cycle will berepeated. A more complete description of the features and functioning ofthe thermopump 14 will be found in the above mentioned Kleen patent.

From the brief description just given, it can be seen that the operationof the thermopump 14 will result in a continual cyclical delivery of hotvapor to the condenser tube 34, and that during the expulsion stroke ofthe pump, liquid heated by the vapor will be forced out of the condensertube. If the volume of the coupling between the condenser 34 and thecheck valves 37, 39 is less than that of the pump stroke, hot liquidwill pass through the check valve 39 into the blanket inlet tube 26 oneach pumping stroke. Thus, it can be seen that the thermopump 14 ispeculiarly adapted for utilization in a person-a1 heating system of thetype with which the present invention is concerned for the reason thatthe application of heat can be utilized both to obtain the necessarycirculating action and to heat the liquid being circulated.

While the flow of liquid to and from the pump 14 is cyclical, ratherthan unvarying or continuous, the flexibility of the various tubes andtubing circuits is more than adequate to accommodate the small changesin liquid volume in the system outside the pump 14.

While the heat for generating vapor can be supplied in a number ofdifferent ways, a flame operated system is of particular utility forportable apparatus. So far as is known, the system of the presentinvention provides the first entirely practical portable individualheating or co0ling apparatus to be proposed. For example, utilizing afuel such as bottled propane gas or the like, readily available in smallcontainers occupying only a few cubic inches of space and weighing aboutone pound, a system of the type just described is ideally suited forindividual use in cold areas. Such a system is particularly useful forevacuation of wounded military personnel from the field of action whereweight and bulk of the protective apparatus must be kept at a minimum,and yet where some form of heating is frequently vital to prevent shock.Using a fuel supply of the type just indicated, it is entirely feasibleto have a complete system capable of delivering 1500 B.t.u./hr. to theblanket for 10 hours and weighing less than 15 pounds, includingblanket, pump and fuel. Of course, for heating applications in extremecold, an anti-freeze liquid such as alcohol or the like will be used asthe circulating medium. Water and other liquids are suitable insituations where the ambient temperature will permit use of higherfreezing point liquids.

In domestic as well as military applications, sportsmen and others whohave occasion to require some type of artificially supplied personalheating in remote localities where electrical power is not available canuse such an apparatus to advantage. Of course, while a bottled gas suchas propane may be most convenient to use, other fuels such as woodalcohol, kerosene and the like can also be used where appropriate.

As is shown in FIG. 4, the pump in the heating system of FIGS. 1 and 2can as well be provided with an electrical heating element 31 wound onthe generator tube 29 in place of the flame heater 3!) of FIG. 1. If thepump is of metal construction, a layer of insulation 33 will be placedbetween the heater 31 and the generator tube. With an electricallyheated pump as shown in FIG. 4, the apparatus of FIGS. 1 and 2 hasimportant advantages for use in the home. It is essentially noiseless inoperation, and as compared with the conventional electric blanket itinvolves absolutely no risk of burns or electrical shock to the user.

As already indicated, the present invention is equally applicable to apersonal heating unit in the nature of a suit or garment as well as theblanket-type heat exchange structure shown in FIGS. 1 and 2. The tubing12 can be sewn into such a garment as Well as in a blanket. For example,as shown in FIG. 5, the tubing 12 can be arranged in circuits throughthe body, arm and leg portions of a coverall type garment 40, with thepump and a fuel container assembled in a cylindrical unit 42 hangingfrom the garment 40 at the beltline. At least one of the tubing circuits12 normally will be provided in each of the arm and leg portions of thegarment 44 with the cir- 'cuit'12 preferably being connected in parallelbetween inlet and outlet tubes 26, 28. Of course, a greater number ofcircuits 12 can be provided for more uniform heat distribution ifdesired.

FIG. 6 is a somewhat enlarged View of the pump and fuel containerassembly 42 of FIG. 5. As shown in FIG. 6, the upper portion of theassembly 42 comprises a cylindrical shell 43 housing the pump 14 (notshown in FIG. 6) and having a flue outlet opening 44 in the upper endthrough which to discharge exhaust gases from a burner 46 in the lowerpart of the shell 43. The burner 46 is coupled to a cylindrical fuelcontainer 48 by means of a threaded cap 50 in the bottom of the shell 43into which the fuel container 48 can be screwed readily for quickinterchange of fuel cartridges. A control knob 52 is mounted on theupper end of the housing 43 beside the flue outlet 44 for adjusting theburner output as described hereinafter. The lower end of the housingshell 43 is perforated as at 54 to'supply combustion air for the burner46 and cooling air for the pump condenser. A hook 56 at the top of theshell provides a support for suspending the assembly 42 as shown in FIG.5.

In FIG. 7, there is shown in somewhat greater detail a thermopump systemprovided with controls for regulating the delivery of heat to a blanketor garment, as in FIGS. 1-4, and including a slightly modified type ofthermopump.

In the FIG. 7 apparatus, there is provided a fuel container 48,containing a combustible gas such as propane or the like. On the outletline from the gas container 48, there is provided a pressure regulatingvalve 49 for eliminating fuel pressure vairations due to ambienttemperature variations and the like. Downstream from the pressureregulating valve 49, there is provided a manually controlled valve 51,operable by a control knob 52, for adjusting the flow of fuel. The valve51 connects to a burner nozzle 46 which is disposed in the lower end ofa flue 44.

Extending laterally into the flue 44 immediately above the burner 46 isthe vapor generator tube 62 of a thermopump 14a, certain features ofwhich are described and claimed in a copending application of R. E.Coleman, filed July 5, 1952, Serial No. 297,371, and assigned to theassignee of the present invention.

The lower end of the generator tube 62 is connected to a generallyvertical cylindrical tube 66 which comprises a combined reservoir andvapor collecting chamber. The upper portion of the generator 62 is ofinverted U- shape and opens into the top of the vapor collecting chamber66 at a point slightly off center.

In the center of the top of the vapor collecting chamber 66, a vaporoutlet tube 68 protrudes down into the chamber 66 for a short distance,and extends from the chamber 66 to a condenser tube 70 in a mannersimilar to the vapor tube 32 in the pump 14 of FIG. 1. The condenserchamber 70 is connected at the bottom into the chamber 66, while the topof the condenser tube 70 is coupled through a check valve 39 to a heatexchanger 74 comprising a coil of several turns around the flue 44 inthe vicinity of the generator arm 62. It will be understood that thefree end of the coil 74 will be connected to a header (not shown in FIG.7) such as the header 16 in FIG. 1. Similarly, a return line 28 from asecond header (not shown in FIG. 7) is connected to the condenser 70through a second check valve 37.

Inside the vapor collecting chamber 66, there is provided a float 76which will rise and fall in the chamber 66 as vapor is alternatelycollected in and discharged from the chamber 66.

The system shown in FIG. 7 will be put in operation by igniting theburner 46 to provide a flame inside the flue 44. The flame will envelopethe generator 62 and at the same time supply heat to the heat exchangercoil 74. Vapor generated in the generator 62 will pass over into the topof the vapor collecting chamber 66 and accumulate therein, at the sametime forcing liquid downwardly in the chamber 66 and up and out throughthe condenser tube 70. Prior to vapor accumulation, the float 76 willperform one of its functions, i.e., preventing the flow of heated liquidup and out through the vapor tube 68, prior to collection of vapor inthe top of the chamber 66.

As vapor continues to collect in the collector 66, the liquid leveltherein eventually will drop sufficiently to allow the float '76 to dropaway from the vapor tube 63. Thereafter, as further quantities of vaporare collected in the collector 66, the float 76 will act as aninsulating separator, reducing heating of the liquid to preventoverheating of the pump system.

When the level of the liquid in the chamber 66 drops below the lowermostpoint in the vapor tube 68, the pump will cycle in the same manneralready described in connection with pump 14 in FIG. 1. However, it isto be noted that as the liquid level rises in the chamber 66 during thecondensing or suction portion of the pump cycle,

the float 76 will seal off the vapor outlet tube 68 before liquid hascompletely refilled the chamber 66. This tends to maintain a quantity ofvapor in the top of the collector 6-6 at all times, thereby facilitatingthe start of the next expulsion or pressure stroke of the pump.

It will be understood that by adjusting the control knob 52, the amountof heat supplied to the pump can be adjusted as required, simultaneouslychanging both the pumping rate and the amount of heat put into thepumped liquid at he heat exchanger coil 74. While the heating of theliquid within the pump itself is adequate for moderately low ambients,the heat exchanger 74 is advantageous for operation under extreme coldconditions.

As an alterntive to the manual control of heating illustrated in FIG. 7,it is quite feasible to have thermostatic control of the pump operationor of the temperature of the circulated liquid. In other words, thetemperature of the liquid being circulated can be thermostaticallycontrolled Without altering the pump output, or both the pump output andliquid heating can be controlled automatically by use of a thermostaticvalve supplementing or replacing the manual valve 51 in FIG. 7.

For example, as shown in FIG. 8, the manual valve 51 of FIG. 7 can bereplaced by a thermostatic fuel control valve 78 disposed in the returnline 28 to be bathed by and responsive to the temperature of the liquidreturning from the blanket through the tube 23. This, of course, willcontrol pump output and liquid heating simultaneously. Alternatively, asshown schematically in FIG. 9, the heat exchange coil 74 of FIG. 7 canbe connected in parallel with a by-pass line 74a to a two-waythermostatic liquid flow control valve 86 disposed in the return line 28to be bathed by the return fluid from the blanket. In this case, thethermostatic valve 80 is arranged to direct more fluid through theby-pass 74a and correspondingly less through the heat exchange coil '74as the temperature of the returning liquid from the blanket increases.Of course, a combination of both types of control illustrated in FIGS. 8and 9 is entirely feasible.

As previously indicated, the apparatus of the present invention can beused for personal cooling as well as for heating. In the apparatus ofFIG. 1, for example, if the volume of the coupling between the condensertube 34 and the check valves 37, 39 is greater than the volume of onestroke of the pump 14, it is theoretically possible to keep hot liquidfrom passing the outlet check valve 39. Under these conditions, liquidwill be circulated through the circuits 12 in the blanket 8 without anyheating by the pump. The circulating liquid will, however, absorb heatfrom a person covered by the blanket, and this heat will be lost as theliquid circulates through circuits relatively remote from thebody-covering area. Thus, a definite cooling action will be obtainedeven though the temperature of the circulating medium is notartificially forced below the ambient temperature. In fact, experimentsshow that circulating a liquid at temperatures only a few degrees belowthe ambient may create a definitely uncomfortable chilly condition, ifthe area of body contact is at all extensive.

Investigation also has shown that there is a psychological factorinvolved in cooling that has bearing on the apparatus used for cooling,and the way in which it is used. This is based on the fact that theaverage individual is accustomed to having his head exposed and the restof his body covered. This means the individual is also accustomed to aslightly higher ambient temperature close to the body below the neck ascompared to a similar area about the head. It has been found, therefore,that a cooling blanket, while cooling the body, is not necessarily theonly satisfactory cooling medium, because as long as the head is cooledeven slightly, it is found that one can be quite comfortable on a verywarm night. In other words, a satisfactory cooling effect can beobtained with a cooling pillow under the head as well as with a coolingblanket over or under the body. Experiments have shown that a personusing a cooling pillow as contemplated herein can be quite comfortableunder a light blanket when the room temperature is such that the sameperson feels uncomfortably warm without the cooling pillow, even thoughcompletely uncovered.

It should also be noted that a cooling device of the type about to bedescribed is not necessarily limited to use of a thermopump as theliquid circulator, since a mechanical pump can be used that is arrangedto circulate liquid through the cooling circuit without affecting thetemperature of the circulated liquid. However, the use of a thermopumpis deemed preferable since it is essentially noiseless, is lessexpensive, requires less maintenance, and can also be used for acombination heating and cooling system.

In FIGS. 10 and 11 there is shown a personal cooling system arranged inaccordance with the invention. The same apparatus can also be used forheating, as will be explained shortly.

The apparatus shown in FIGS. 10 and 11 includes a thin, flexible heatexchange structure 81 comprising two superposed flexible sheets 82, 83of water-proof material, having approximately the (rectangular)dimensions of an ordinary bedpillow. The sheets 82, 83 preferably are ofplastic material, such as one of the so-called vinyl plastics. The twosheets 82, 83 are sealed together along the edges and along spaced lines84 to define in the unsealed areas between the sheets 82, 83 integralpassages 86 through which to circulate cooling liquid.

Even though the cooling element 81 of FIGS. 10 and 11, when used in themanner described hereinafter, will tend to keep the user comfortablycool, it is possible for small quantities of moisture to accumulateunder the users head and create a clammy feeling. Accordingly, in thesealed surface areas 84 between the conducting passages 86, the coolingelement 81 preferably is perforated as indicated at 88 so that moisturewill not accumulate on the waterproof surface (82 or 83).

In the cooling element presently being described, as compared with theblanket structure of FIGS. 1 and 2, it is seen that the passages 86 arearranged in a continuous circuit between the inlet and outlet tubes 26,28, rather than all in parallel as are the tubes 12 in the FIGS. 1 and 2construction. The reason for this is that in the system of FIG. 10, heatexchange between the user and the circulating liquid is more a matter ofconduction than of convection. In other words, it is contemplated thatthe user will lose heat to the surface of the cooling element 81 bycontact therewith (with, perhaps, a pillowcase or the like separatingthe users head from the cooling surface). Accordingly, for bestefficiency, the circuit 86 should be arranged so that no matter howlimited the area of user contact, substantially all of the coolingmedium will flow through that area. In the case of the heating blanket,on the other hand, what is contemplated is the creation of a warmambient about the users body, rather than direct heat exchange contactbetween the users body and the warm surface. Therefore, it is notessential that the warming liquid flow through every one of the blanketcircuits to every portion of the blanket, but merely that the heatedliquid flow through a major part of the blanket to create warmth beneaththe blanket which will dispel itself over the entire area covered by theblanket. Secondly, if all of the passages in the cooling element 81 wereconnected in parallel between the inlet and outlet tubes 26, 28 thepressure of the users head might well divert all of the cooling flowthrough passages remote from the users head, and the cooling effectwould be lost. Of course, it is entirely permissible to have two or moreparallel circuits through the cooling element, provided that all of thecircuits are substantially coextensive and all extend throughsubstantially the entire area of the cooling element. This will befurther clarified in connection with the description of FIG. 12hereinafter.

In the embodiment of the invention illustrated in FIG.

10, a pairof check valves 37, 39 are provided in the inlet and outletlines 26, 28. A relatively long (i.e. large volume) tube and arelatively short (i.e. small volume) tube 92 are connected in parallelbetween a thermopump 14 and the check valves 37, 39, through a selectorvalve 94 that permits the user to select either the long line 90 or theshort line 92 as the coupling, as explained hereinafter.

In use, it is contemplated that the cooling device 81 will be insertedbetween the pillow body and the pillowcase of an ordinary bedpillow.Assuming that the valve 94 has been set as in FIG. 10 to complete acircuit to the pump through the line 90, and with the entire system ofFIG. 10 filled with liquid, such as water, operation of the thermopump14 will establish a cyclical flow of liquid back and forth in the line94 This will force liquid through the check valve 39, around through thepassages 36, and back through the check valve 37 as the liquid movesback and forth in the isolation line 90. As the liquid passes under theusers head, it will absorb heat, and will then lose this heat duringcirculation through parts of the element 81 remote from the users headand through the coupling lines 26, 28. The relatively large volumecoupling line 90 will ensure against any transfer of heat from the pumpto the cooling element 81.

In order to use the apparatus of FIG. 10 as a heating system, the valve94 will be adjusted to place the short line 92 in the circuit ratherthan the long line 94. This will couple the pump 14 closely to theelement 81 so that, on each pump stroke, heated liquid will flow fromthe pump 14 past the check valve 39 and into the passages 86.

Due to the flexibility of the element 81, it is possible that the weightof a users head may materially restrict one or more of the passages 86,cutting down the flow of cooling fluid. This effect can be substantiallyovercome the charging the system with fluid at a pressure slightly aboveatmospheric pressure to help maintain the crosssectional shape of theflow passages. For example, a filling pressure of the order of one poundper sq. inch has been found adequate and yet does not make the element81 objectionably stiff or rigid.

When using the apparatus of FIG. 10 for cooling, the large volumeisolation link 94] between the thermopump condenser chamber and thecheck valves 37, 39 will insure against heat transfer from the pump tothe cooling medium. However, this means that the pump condenser will nothave the benefit of drawing in relatively cool liquid on each suctionstroke. Depending on the heat loss characteristics of the coupling linefrom the condenser to the check valves, it is possible for the condenserto overheat under these conditions so that the thermopump will fail tooperate due to failure of condensation.

Again, it is sometimes found that when the cooling element 31 isinserted in a pillow as just described, the pillowcase does not allowenough heat loss from the circulating liquid to obtain the desiredcooling effect.

To avoid these difficulties, auxiliary cooling circuits both for thepump and for the cooling element sometimes can be used to advantage. Anarrangement illustrating the use of such auxiliary cooling circuits isshown in FIG. 12. The FIG. 12 system also includes a preferred form ofcooling element, as well as a circuit arrangement whereby the system canbe used either for heating or for cooling, as desired.

In the FIG. 12 apparatus, a thermopump 14 is connected to circulateliquid through a heat exchange element 81a. Between the pump 14 and theelement 81a in FIG. 12, there is provided an auxiliary cooling orisolation circuit for the pump 14, comprising a tube 96 and a pair ofcheck valves 98, 1%. Between the check valves 98, 100, a T connection192 leads to the cooling element circuit through an isolating line 104.

To provide extra cooling for the liquid circulated through the element81a, the system of FIG. 12 includes a pair of relatively long inlet andoutlet lines 26a, 28a, rather than the comparatively short lines 26, 28utilized in the FIG. system.

The cooling element 811: in FIG. 12 is made up in a manner similar tothat shown in FIG. 11; e.g., by sealing together two superposed sheets82, 83 of waterproof material along spaced lines 84 to define liquidconducting passages 81a-81p in the unsealed areas between the sheets 82,83. In the FIG. 12 element, however, the circuit arrangement is somewhatdifferent. In the FIG. 10 element 81, it will be noted that the circuitextends from the corner where the liquid inlet 26 is located, to thediagonally opposite corner, along a devious path that extends back andforth across the element 81, and then returns directly along the edge ofthe element to the outlet opening connecting with tube 28.

If the element 81 is contacted by the users head in any given area, thesurface downstream from that area will contain relatively warm liquid,while upstream from that area the liquid will be cool incoming liquid.Thus, a fairly well defined separation will exist between the warm andthe cool surface areas. Experiments have shown that this is not entirelydesirable. Since the cooling effect or distribution of cool liquid isnot uniform across the element 81, there is a tendency for the user tomove about restlessly in an attempt to use only the coolest part of theelement. In order to overcome this tendency, it has been found desirableto distribute the circuits in such a manner that passages containingrelatively cool incoming liquid will be intermingled with passagescontaining outgoing relatively warm liquid, so that the relatively warmand cool liquid areas will not be sharply separated but will be mingledin such a manner that the user will not prefer one area of the elementto another.

A preferred circuit arrangement for accomplishing this is shown in theelement 81a in FIG. 12, wherein subscripts a-p have been added to thepassage numerals 86 to facilitate discussion.

To avoid confusion, it should be noted first that the passages 86a-86pare connected together to form two substantially identical circuitsextending between the inlet and outlet connections 26a, 28a. This hasthe effect of decreasing the pressure drop or resistance to flow throughthe cooling element for a given flow rate. For simplicity, in thefollowing discussion, it will be assumed that only a single circuit isinvolved.

Starting from an origin point at the inlet tube 26a, in the upperlefthand corner of the element 810: as viewed in the drawing, thecircuit extends along a devious path through passages 86a-86g,traversing substantially the entire area of the element 81, to arelatively remote point (i.e., the lower lefthand corner of the element81a. The circuit then returns to a terminal point at the outlet tube 28athrough passages 86h-86p along a path substantially coextensive with andclosely paralleling that followed by the passages 86a-86g, so that thepassages containing relatively cool incoming liquid are paralleled bypassages containing relatively warm outgoing liquid. Of course, thepoint at which the temperature of the liquid increases will be dependenton the location of the users head. However, with the circuit arrangementshown, wherein the circuit is, so to speak, folded back on itself, theparalleled incoming and outgoing liquid paths will distribute thecooling effect more uniformly and across a greater part of the element81a than in the case of the circuit in the element 81.

While the foregoing discussion has been directed primarily to the caseof a bedpillow type of cooling element, it should be noted that theinvention is by no means thus limited. For example, a larger element ofsimilar construction can also be used for cooling, in the same manner,as a mattress cover, an automobile seat cover or the like.

The pump 14 is arranged to be connected to the cooling 10 elementcircuit in FIG. 12 either directly, or through the isolation line 104,by means of a selector valve 94, so that the heat exchange element 81acan be used either for heating or cooling.

For example, if the FIG. 12 system is to be used for cooling, theselector valve 94 will be set in the position shown to couple the pump14 to the element 81 through the isolation circuit 104. This will causehot liquid forced from the pump 14 to flow past the valve 100, and thishot liquid will cool considerably before being returned through thevalve 98 several cycles later. As before, the reciprocating motion ofthe liquid in the isolation tube 104 will cause cooling circulationthrough the element 81 and the coupling lines 26a, 28a- If, on the otherhand, the system is to be used for heating, the slector valve 94 will beset to couple the pump 14 directly to the inlet line 26a. This willforce hot liquid from the pump 14 directly into the circuit of theelement 81a on each pump stroke. Since the liquid drawn back into thepump from the outlet line 28a will have lost most of its heat, theauxiliary cooling circuit 96, 93, will not be needed.

A somewhat simpler substitute for the auxiliary pump-cooling circuit96-100 of FIG. 12 is shown in FIG. 13. This comprises a tank 106, ofvolume several times that of the pump stroke, in place of the tube 96and check valves 98, 100. The tank 106 also can serve as a collector forany air inadvertently trapped in the system when it is filled. In fact,a small quantity of air can purposely be trapped in the tank 106, bothto serve as a cushion for absorbing the pump stroke if the coolingcircuit is inadvertently kinked off, as well as a thermal isolator forreducing the required volume of the isolation line 104. In operation,the hot liquid discharged from the pump will rise to the top of the tank106 on each pressure stroke, While on the suction stroke the pump willrefill with relatively cool liquid from the bottom of the tank. At thesame time, any air in the system will gradually work its way to thehighest point in the tank where it will collect and serve the cushioningand isolation functions already stated.

If desired, the control valve 94 in the systems of FIGS. 10-13 can be inthe form of a thermostatic valve, arranged as shown in FIG. 14, to holdthe maximum temperature of the circulated liquid at some preselectedlevel. The thermostatic valve 108 is placed in the outlet line 28a tosense the temperature of the liquid leaving the heat exchange structure81a. With such an arrangement, an increase in the temperature of theliquid leaving the element 81a will cause the valve 108 to divert someof the liquid leaving the pump 14 to flow through the isolation circuit96-100, thereby decreasing the heat input to the element 81a. In warmweather, of course, the thermostatic valve 108 will automatically divertall of the pumped liquid to flow through the isolation circuit 96-100,thereby setting the system for cooling action as previously described.

We claim:

1. A flexible heat exchange plastic panel structure adapted to be placednear portions of the human body in heat-exchange relationshi therewithcomprising super posed sheets of flexible, waterproof plastic material,said sheets being sealed together along spaced lines to define an inletconnection and an outlet connection at a first edge of said panelstructure, said outlet connection being adjacent to said inletconnection, said inlet connection branching into a plurality of separateliquid conducting passages extending through the unsealed areas betweensaid sheets, said passages being joined to form a plurality ofcontinuous circuits extending along a devious path, traversingsubstantially the entire area of said structure, said circuits beginningat said inlet connection and extending across said panel structure to anarea near the opposite edge and then turning and extending back acrosssaid panel structure to an area near said first edge and then 1 1turning away from said first edge and again extending across said panelstructure to an area remote from said inlet and outlet connections, saidcircuits returning from said remote area to said outlet connection alonga path in said panel structure substantially coextensive with andclosely paralleling the path followed by said circuits in extending tosaid remote area.

2. A flexible heat exchange panel adapted to be placed near portions ofthe human body in heat-exchange relationship therewith comprising twosheets of flexible waterproof plastic material, said sheets being sealedtogether along a plurality of pairs of continuous lines defining aplurality of liquid-conducting passages between said pairs of lines,said lines defining an inlet at one edge of said panel connected to aplurality of liquid-conducting passages that return to an outlet at saidedge of the panel near said inlet, said plurality of liquid-connectingpassages being in parallel flow relationship between said inlet andoutlet and traversing back and forth across said panel and extendingfrom said inlet to an area in said panel remote from said inlet and thentraversing back and forth across said panel and returning from saidremote area to said outlet, the portions of said passages returning fromsaid remote area closely paralleling the portions of said passagesextending to said remote area, and said panel having a multiplicity ofperforations therethrough between said passages.

References Cited by the Examiner UNITED STATES PATENTS 1,896,953 2/33Hassell 165-46 2,062,864 12/36 Clark et al 16546 2,250,325 7/41 Barnes16546 2,397,232 3/46 Barnes et al. l65-46 2,540,547 2/51 Rodert 16546FOREIGN PATENTS 746,650 8 4 Germany.

ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner.

2. A FLEXIBLE HEAT EXCHANGE PANEL ADAPTED TO BE PLACED NEAR PORTIONS OFTHE HUMAB BODY IN HEAT-EXCHANGE RELATIONSHIP THEREWITH COMPRISING TWOSHEETS OF FLEXIBLE WATERPROOF PLASTIC MATERIAL, SAID SHEETS BEING SELAEDTOGETHER ALONG A PLURALITY OF PAIRS OF CONTINUOUS LINES DEFINING APLURALITY OF LIQUID-CONDUCTING PASSAGES BETWEEN SAID PAIRS OF LINES,SAID LINES DEFNING AN INLET AT ONE EDGE OF SAID PANEL CONNECTED TO APLURALITY OF LIQUID-CONDUCTING PASSAGES THAT RETURN TO AN OUTLET AT SAIDEDGE OF THE PANEL NEAR SAID INLET, SAID PLURALITY OF LIQUID-CONNECTINGPASSAGES BEING IN PARALLEL FLOW RELATIONSHIP BETWEEN SAID INLET ANDOUTLET AND TRAVERSING BACK AND FORTH ACROSS SAID PANEL AND EXTENDINGFROM SAID INLET TO AN AREA IN SAID PANEL REMOTE ROM SAID INLET AND THENTRANSVERSING BACK AND FORTH ACROSS SAID PANEL AND RETURNING FROM SAIDREMOTE AREA TO SAID OUTLET, THE PORTIONS OF SAID PASSAGES RETURNING FROMSAID REMOTE AREA CLOSELY PARALLELING THE PORTIONS OF SAID PASSAGESEXTENDING TO SAID REMOTE AREA, AND SAID PANEL HAVING A MULTIPLICITY OFPERFORATIONS THERETHROUGH BETWEEN SAID PASSAGES.